The invention concerns a switchable lever for a valve train of an internal combustion engine, said lever comprising side walls connected by a crossbar and further comprising on one end, a bearing for enabling a pivotal support of said lever and, on another end, on an underside of said crossbar, a support for at least one gas exchange valve, said crossbar comprising between said one end and said another end, a recess which is bridged by a cam roller axle mounted in bores of said side walls, which lever, for switching to a high valve lift, can be brought into contact with at least one high lift cam and, for switching to a low or a zero valve lift, can be brought into contact with at least one low lift cam or one zero lift cam.
Switchable levers of the aforesaid type are sufficiently well known in the technical field and must not be described in detail in the present context. In the final analysis, such levers possess two arms, of which, a first arm serves for a contact with a high lift cam and a second arm seated in a recess of the first arm or laterally to this, serves for a contact, for example, with a low lift cam. Switching to the high lift cam is effected through coupling pistons which extend in one of the levers and, for achieving coupling, are displaced partially into the other lever. The arm destined for contact with the high lift cam usually comprises sliding surfaces for contact with this cam, whereas the arm for contact with the low lift cam possesses either a cam roller or likewise a sliding surface.
It is noted that the prior art levers have a structure that is too complex, are made up of too many separate parts and have an excessive design space requirement. Due to their relatively large mass, an undesired large amount of friction work is performed during operation. Due to the asymmetrical loading, depending on the structure in each case, the lever also develops an undesired tendency to tilt. A coupling lash in the coupling region has to be maintained, i.e. a minimum idle travel of the coupling element until it reaches its entraining surface on the other arm for achieving coupling. The adjustment of this coupling lash, which can even increase during operation, as also the guaranteeing of a reliable displacement of the coupling element, once the coupling command has been initiated, prove to be excessively complex.